Guardrail systems are widely used along heavily traveled roadways to enhance the safety of the roadway and adjacent roadside. Guardrail beams and their corresponding support posts are employed to accomplish multiple tasks. Upon vehicle impact, a guardrail acts to contain and redirect the errant vehicle.
For many years, a standard heavy gauge metal guardrail known as the “W-beam” has been used on the nation's roadways to accomplish these tasks and others. Named after its characteristic shape, the “W-beam” is typically anchored to the ground using posts made of metal, wood or a combination of both.
Wood posts are more readily available and more economical than metal posts in some geographical areas. In other areas, metal (e.g., steel) posts are more readily available and more economical, and are preferred for their ease of installation using driving methods.
Wood posts used in a terminal portion of a guardrail have been made to break away upon impact, thus producing a desired behavior during a collision by a vehicle at the end of the terminal section. However, in some environments, wood posts deteriorate more rapidly and alternate materials are sought. Commonly used steel posts do not break away in the desired fashion, and are not suitable for use in the terminal section of a guardrail system.
Break away steel support posts that are modified to allow for failure during a collision have recently become available. Examples include a “hinged breakaway post” and the “energy absorbing breakaway steel guardrail post” described in U.S. Pat. No. 6,254,063. Many such prior attempts require substantial time, money, and resources during fabrication, modification, and/or installation.